This invention relates to a porting arrangement for a multi-valve engine and more particularly to an improved porting arrangement for such an engine which has plural inlet and plural outlet ports for the same combustion chamber of the engine.
The use of multiple valves for an internal combustion engine as a means for increasing performance for a given displacement is well known. Although the advantages of multiple valves are well known, the cost and complexity associated with multiple valve engines has limited wider use of them.
For example, when multiple valves are employed, the associated porting of the cylinder head becomes quite complicated. That is, if there are provided plural valves for an engine, it has been normally the practice to provide either plural ports, one for each valve, or a siamesed arrangement wherein all of the valves are served by the same port. Although the latter approach has the advantage of simplicity, when multiple valves are employed, there are times when it may be desirable to provide either multiple inlets or multiple outlets for the valves. For example, if the multiple valves are intake valves, it may be desirable to assure the use of plural charge formers for each chamber of the engine. When this occurs, the engine porting arrangement may have two inlets, a common passage and plural outlets. However, it is desirable to insure a smooth transition between the inlets and the outlets.
It is, therefore, a principal object of this invention to provide an improved, simplified and high efficiency arrangement for a multiple valve engine.
It is a further object of this invention to provide a multiple valve arrangement wherein the port is provided with a pair of communicating passageways that communicate with the combustion chamber through a single port but wherein flow transitions can be improved.
In connection with the specific type of arrangement previously described wherein there are multiple inlets and outlets and it is desirable to provide separation between some of the passages, the cylinder head casting can become quite complicated. That is, if two inlets must merge into a common passageway and then again diverge into plural passageways, it is very difficult to form the cylinder head casting in a simple and efficient manner.
It is, therefore, a still further object of this invention to provide an improved arrangement for providing plural passageways communicating with a common port and wherein the transition can be smooth and the plural passageways can be conveniently and simply formed.
It is a further object of this invention to provide a porting arrangement for an engine wherein a single cylinder head port is served by several passageways and the individual passageways are formed by a separate member that can be conveniently and easily attached to the cylinder head and which will provide a smooth transition.